Ulfang has asked you to slay Garwal. Then, return the Worg Disguise to Watcher Moonleaf at Steel Gate.
When you've eaten Talonshrike's eyes, you should be able see Garwal and rip out his throat!
<Race>-thing, seek out and slay Garwal in the western Rivenwood. After you have killed him, go and tell Moonleaf that I am once more the alpha worg!